2020年12月26日 · Calculate sin(80)° Determine quadrant: Since our angle is between 0 and 90 degrees, it is located in Quadrant I. In the first quadrant, the values for sin, cos and tan are …

2018年8月10日 · Let , #X=sin20^circsin40^circsin60^circsin80^circ# #:.X=1/2(sin60^circsin20^circ)(2sin80^circsin40^circ)# Using , #"Product Identity"#

2016年9月26日 · This formula can be simplified to -sin60=-sqrt(3)/2 sin20cos80-cos20sin80=sin(20-80)=sin(-60)=-sin60=-sqrt(3)/2

2015年11月2日 · (sin 80^@ - sin 10^@)/(sin 80^@ + sin 10^@) = tan 35^@ sin a ± sin b = 2 sin ((a±b)/2) cos ((a∓b)/2) tan A = sin A/cos A (sin 80^@ - sin 10^@)/(sin 80^@ + sin 10 ...

Here is an example of using a sum identity: Find #sin15^@#.. If we can find (think of) two angles #A# and #B# whose sum or whose difference is 15, and whose sine and cosine we know.

Prove that sin 10° + sin 20° + sin 40° + sin 50° = sin 70° + sin 80°. Get the answers you need, now!

2018年5月21日 · 24. Here, "the Nr."=96sin65^@sin35^@sin80^@, =48{2sin65^@sin35^@}sin80^@, =48{cos(65^@-35^@)-cos(65^@+35^@)}sin80^@, …

2018年6月1日 · How do you use an addition or subtraction formula to write the expression as a trigonometric function of one number and then find the exact value given #cos(80)cos(10) …

2019年7月27日 · Step-by-step explanation:L.H.S. = 2sin15cos5+2sin45cos5 [ using sin C+sin D= 2sin C+D/2 cos C-D/2 for sin10+sin20 & sin40+sin50]= 2cos5 (sin15+sin45)= 2cos5…

You would need an expression to work with. For example: Given #sinalpha=3/5# and #cosalpha=-4/5#, you could find #sin2 alpha# by using the double angle identity